Finger bars for pulpwood grinders

ABSTRACT

A pulpwood grinder including a power driven pulpstone, a pocket adapted to receive a supply of wood to be processed from which the wood is urged against the pulpstone and a finger bar positioned in close proximity to the pulpstone, the finger bar having spaced, angled fingers angled relative to the pulpstone rotational axis for directing pulp laterally toward the axial ends of the pulpstone, the spaces between the angled fingers providing restricted openings which hinder movement of slivers and other debris to facilitate further grinding action thereon and enhanced reduction to pulp.

United States Patent 1 Cryderman May 22, 1973 541 FINGER BARS FOR PULPWOOD 1,742,233 1 1930 Chappell ..24l/282 x GRINDERS 3,528,618 9 1970 Ullner ..241 2s2 Primary Examiner-Granville Y. Custer, Jr. Attorney-Andrew J. Beck and Charles W. Walton [57] ABSTRACT A pulpwood grinder including a power driven pulpstone, a pocket adapted to receive a supply of wood to be processed from which the wood is urged against the pulpstone and a finger bar positioned in close proximity to the pulpstone, the finger bar having spaced, angled fingers angled relative to the pulpstone rotational axis for directing pulp laterally toward the axial ends of the pulpstone, the spaces between the angled fingers providing restricted openings which hinder movement of slivers and other debris to facilitate further grinding action thereon and enhanced reduction to pulp.

7 Claims, 7 Drawing Figures Patented May 22, 1973 3,734,419

2 Sheets-Sheet 2 INVENTOR GEORGE W. CRYDERMAN 1 FINGER BARS FOR PULPWOOD GRINDERS BACKGROUND OF THE INVENTION 1. Field of the Invention The instant invention relates generally to pulpwood grinders, and more particularly to unique improvements in the finger bars utilized with such grinders.

2. Description of the Prior Art The pulpwood grinding industry has long been aware of the sundry problems posed by the necessity of securing proper pulp reduction and withdrawal and prohibiting passage of wooden slivers out of a pocket or from one pocket to another in a multiple pocket pulp grinder. Such slivers, if passed with the pulp, adversely affect the quality of the pulp produced by the grinding operations and hence normally require screening of the pulp slurry for removal. Despite recognition of the problems caused by the wood slivers and the attendant necessity of screening, the various techniques adopted within the industry to eliminate sliver production during the reduction process have not been completely successful.

For example, finger bars with a series of rake-like teeth or fingers have been secured in proximity to the rotating pulpstone between adjacent pockets of a multiple-pocket grinder. Such finger bars, as shown in U.S. Pat. No. 1,742,233, granted to F. B. Chappell and U.S. Pat. No. 1,917,420, granted to C.O. Bachman, generally include straight teeth or fingers, the axis of which is perpendicular to the rotational axis of the pulpstone.

While somewhat helpful, such finger bars have sometimes proven unsatisfactory in operation for a number of reasons. To illustrate, the plurality of parallel fingers the axis of which is perpendicular to the stone rotational axis have not always adequately impeded the passage of slivers out of a pocket or toward the adjacent pocket on the grinder. These slivers tend to accumulate upon the upstream face of the next adjacent finger bar of an adjacent pocket, thereby interferring with proper reduction thereof. In addition, slots between the parallel fingers of the finger bar sometimes become jammed with slivers, ground pulp, and the like. Finally, removal of uncontaminated pulp from the stone has been troublesome with conventional arrangements.

BRIEF SUMMARY OF INVENTION Thus, with the deficiencies of the prior art structures in mind, the instant invention contemplates finger bars having laterally spaced, angularly-oriented fingers angled relative to the pulpstone rotational axis for directing pulp to the lateral ends of the pulpstone from whence pulp falls to a subadjacent pulp collector. Angular orientation of the fingers is additionally advantageous in that it has been found that this orientation hinders sliver movement out of a pocket and increases the grinding action thereon, thereby enhancing pulp quality.

Other objectives realized by the instant invention will be apparent from the following description of a preferred embodiment of finger bars of unique design.

BRIEF DESCRIPTION OF DRAWING FIG. I is a side elevation of the central section of a multiple pocket pulp grinder, portions thereof being broken away to more clearly depict the environment within which the instant invention functions;

FIG. 2 is a front elevational view of a section of a finger bar constructed in accordance with the principles of the instant invention;

FIG. 3 is a side elevation of the finger bar, such view being taken along line 33 in FIG. 2 and in the direction indicated;

FIG. 4 is a bottom plan view ofa section of the underface of the finger bar, such view being taken along line 4-4 in FIG. 3 and in the direction indicated.

FIG. 5 is a front elevational view of a section of a finger bar showing an alternate embodiment of the instant invention;

FIG. 6 is a side elevation of the finger bar shown in FIG. 5 and taken along line 6-6 thereof, and

FIG. 7 is a bottom plan view of the underface of the finger bar shown in FIG. 6 and taken along line 77 thereof.

DETAILED DESCRIPTION OF INVENTION Turning now to the drawings, wherein like reference numerals indicate like components, a multiple pocket pulp grinder is indicated generally by reference 10 and basically includes a pulpstone 12. The stone 12 is secured to a drive shaft 14 which is rotated at high speed, in a counterclockwise direction, by conventional power sources (not shown) so that the abrasive peripheral surface of the stone reduces the logs pressed thereagainst into pulp.

A first magazine 16 for storing a supply of material to be reduced, such as pulpwood bolts or logs, issituated at the upper right side of stone l2, and a first or up-running pocket 18 receives a charge of logs from magazine 16. Pulp is collected in a trough-like collector 20 situated beneath the floor 22 to which grinder 10 is secured. Magazine 16 includes a removable top 24 and sidewalls 36 and 38 and can be loaded either manually or automatically through the top, as from a conveyor belt (not shown). Gate 26 is operatively disposed between magazine 16 and up-running pocket 18. A motor actuated actuator rod 28 is connected to an upstruck flange on the rear of the gate 26 for moving the gate to a retracted position so that magazine 16 can discharge its contents into pocket 18.

A pressure shoe 30 is connected to a motor actuated piston rod 32 for pressing a charge of logs in pocket 18 against the peripheral face of pulpstone 12. Shoe 30 moves radially inwardly along the path defined by the undersurface of gate 26, sloping guideway 34 and between pocket sidewalls (not shown). The movement of shoe 30 is coordinated with the opening and closing sequence of gate 26 through controls of conventional design (not shown). When shoe 30 is moved radially away from pulpstone 12, gate 26 is opened and a charge is released from magazine 16 into pocket 18. Rod 28 then moves gate 26 radially inwardly to close the magazine and piston rod 32 gradually moves pressure shoe 30 radially inwardly against the logs within pocket 18. Shoe 30 continues to move inwardly until all of the logs held in pocket 18 are reduced and then the cycle of operation is repeated again.

A similar magazine and pocket arrangement is provided on the left side of the pulpstone. A second magazine 44 with a removable top 46, and sidewalls 60, 62, is situated on the upper left side of pulpstone 12. A second or down-running pocket 48 receives a charge of logs from magazine 44, and a second gate 50 is disposed therebetween. Gate 50 is extended and retracted by a motor actuated actuator rod 52 which is connected to an upstruck flange on rear of the gate.

A second pressure shoe 54 connected to a motor actuated piston rod 56 presses the charge of logs in second pocket 48 against pulpstone 12 as the shoe moves radially inwardly along the path defined by the undersurface of gate 50, sloping guideway 58 and between pocket sidewalls (not shown). The movement of pressure shoe 54 is coordinated with the opening and closing sequence of gate 50 through controls of conventional design.

A series of water nozzles or showers 68, 70,. 72 and 74 are spaced about, and along upper and lower peripheries of the stone 12. The showers spray water onto the stone to cool same and to wash away pulp that clings to the face of the stone towards the collector 20.

To direct pulp movement to the axial ends of the pulpstone 12 to facilitate withdrawal thereof, to hinder passage of slivers from the pockets 18 and 48 before complete pulp reduction and to circumvent accumulation of such slivers above the second pocket 48, the present invention provides a novel finger bar construction, arrangement and combination as follows.

Fixed at the upper and lower inner extremities of the first and second pockets 18 and 48, adjacent the pulpstone periphery, are dissimilar pairs of circumferentially spaced, upper and lower finger bars 42, 43 and 66, 67, respectively. The finger bars 42 and 67 may be considered to trail the leading finger bars 43 and 66 in the direction of stone rotation. The leading finger bars, 43 and 66, are conventional in construction insofar as the longitudinal axes of the projecting fingers thereof are straight, parallel and perpendicular to the rotational axis of the stone 12.

According to the present invention, the trailing finger bars 42 and 67 are constructed in a unique manner. As shown in FIG. 3, bars 42 and 67 include a top wall 76, a rear wall '78, a foreshortened bottom wall 80, a front wall 82, and an inclined projecting face 84 that extends between the walls 80 and 82 to a plane immediately adjacent to the periphery of the pulpstone. These surfaces define angularly oriented fingers 73 and 75. The finger bars are mounted to connection bars 92 as shown in FIG. I. Any suitable connectors, such as capscrews or the like, make use of spaced holes 86 t fixably secure the finger bars to their respective connection bar elements which are in turn adjustably secured (not shown) to the grinder housing so that the finger bars are in close proximity to the working face of the pulpstone.

Referring to FIG. 2, each bar, 42 and 67, comprises right and left halves, the fingers 73 on the right half being oppositely angularly directed to the fingers on the left half so that these fingers are adapted to direct pulp towards the adjacent lateral or axial end of the pulpstone 12. Between the laterally spaced fingers 73 and 75, first and second sets of oppositely angularly directed slots 88 and 90 are provided extending outwardly in opposite lateral directions from the centerline of finger bar to channelize the pulp. The slots 88 and 90 are generally U-shaped in front elevation, as shown in FIG. 4. Fingers 73 and 75 have substantially parallel side walls 94, 96 and 98, 100 respectively as shown in FIG. 2.

The angular orientation of the fingers and slots of the finger bars 42 and 67 is of particular significance in that not only does this orientation aid in directing pulp to the axial ends of the pulpstone, but it additionally binders the passage of slivers out of the pockets 18 and 48 by movement through the slots 88 and 90. In this regard, this angular orientation is a substantial improvement over the conventional straight finger bar arrange ment of the prior art. Although the theory of the sliver movement is not fully understood, it has been found that passage of tangentially traveling slivers through the finger bar slots is substantially retarded by the angled fingers of the present invention. Such slivers appear to abut the inclined side walls of the fingers and passage therethrough is thereby hindered. This retarding effect may be enhanced by inclining the finger side walls such that the spacing A shown in FIG. 4 and located between the side walls 94, 96 and 98, at the base of the fingers decreases at some desired rate in the direction towards the outer extremities of the fingers resulting in a smaller spacing at B.

In practice of the present invention, it has been found that the fingers 73 and 75 are oriented 30 to 35 degrees relative to the vertical axis for the best results; however, however angles up to 45 have produced satisfactory results.

As has heretofore been stated, the leading finger bars 43 and 66 are of a conventional type insofar as the fingers thereof are straight, parallel and include a longitudinal axis which is perpendicular to the rotational axis of the pulpstone 12. Such a conventional arrangement at the leading pocket side is preferable in that any slivers that succeed in passing through the slots of the trail-' ing finger bars 42 and 67, are permitted to pass relatively freely through the next leading finger bar into the adjacent pocket without accumulation on the leading finger bar. Straight slotted finger bars facilitate such passage.

In operation pockets l8 and 48 are charged with a supply of logs from magazines l6 and 44. Pressure shoes 30 and 54 urge the logs against the peripheral face of pulpstone l2. Grinding action on the logs produces pulp and objectionable slivers. The present inventive angled finger bars trailing each pocket directs pulp to the lateral or axial ends of stone 12, from whence the pulp falls downwardly into collector 20. Sliver movement out of the pockets is substantially impeded by finger bars 42 and 67, such that additional grinding action thereon causes a reduction of slivers to pulp. Additionally by the arrangement of alternate straight and angled finger bars at leading and trailing ends of adjacent pockets, sliver accumulation on the leading finger bar is circumvented and greater efficiency and pulp quality is secured.

An alternate form of the instant invention, as shown in FIGS. 5-7, provides a finger bar wherein, in addition to including laterally angled fingers, also teaches a construction wherein such fingers are formed with diverging side walls such that the width of the finger decreases in the direction of pulpstone, such construction having been found as reducing material jamming in the spaces between the fingers. As in the previous embodi ment a bar 42' is are adapted to be mounted on a connection bar 92 as shown in FIG. 1 through use of any suitable connectors (not shown) in laterally spaced recesses 104 as shown in FIGS. 5 and 6. A similar bar would also be substituted for finger bar 67. Each bar includes a top wall 106, a rear wall 108, a foreshortened bottom wall 110, a front wall 112, and an inclined projecting face 114 that extends between the walls and 112 to a plane immediately adjacent to the periphery of the pulpstone. These surfaces define angularly oriented fingers 116 and 118 as shown in FIG. 5. The fingers 116 on the right half of the bar are oppositely angularly directed to the fingers 118 on the left half to direct pulp towards the adjacent lateral or axial ends of the pulpstone 12. In the instant embodiment, the spac ing between the adjacent finger sidewalls 120, 122 and 124, 126 increases progressively from points C through E as shown in FIG. 5. As a consequence, finger widths F through I progressively decrease from the finger bars leading to trailing edges as shown in FIG. 7. To further reduce the occurrence of pulp and sliver buildup and jamming of the spaces between adjacent fingers, the finger side walls 122 and 126 (as shown in FIG. 7) are vertically inclined relative to walls 120 and 124 respectively, such that space width J at the root of the finger, as shown in FIG. 7, increases progressively in the direction toward the outer extremities of the fingers resulting in a larger opening K.

The construction wherein the finger side walls diverge in the direction of pulpstone rotation and/or finger sidewalls incline relative to each other as described above, is of particular significance in that it reduces the tendency of pulp and sliver buildup and jamming between adjacent finger bar fingers that has sometimes been a problem in conventional finger bars having constant width fingers having parallel side walls. Although the theory underlying material buildup and jamming is not completely understood, it has been found in practice that jamming of material between adjacent fingers is substantially reduced in the instant embodiment because this construction provides for progressive reduction of the restriction acting on the material in the direction of material flow, and, as a result, appears to aid channelizing of material therethrough.

The description of the embodiments of the invention set forth above is intended to be illustrative and not limiting in nature. Manifestly, various modifications with regard to the impulse angle, size, shape, number, and orientation of the slots on the finger bars could be made without departing from the scope of the instant invention, to be defined with reference to the appended claims.

Having thus described my invention, what I claim as new and desire to secure by letters patent in the United States, is:

1. A finger bar adapt'd for" use in a pulpstone grinder with a rotatably mounted pulpstone, said bar comprising:

a plurality of laterally spaced fingers positioned. transversely relative to the longitudinal axis of said finger bar, said fingers being oriented relative to each other such that the spacing between the side walls of adjacent fingers increases in the direction of pulpstone rotation whereby pulp jamming and material buildup between adjacent fingers is reduced.

2. A finger bar according to claim 1 wherein each of said fingers includes a generally planar surface at the free extremity thereof, said bar further including a base portion between opposed side walls of adjacent fingers and defining therewith the spacing between the opposed side walls, said opposed side walls of adjacent fingers being inclined relative to each other such that the spacing between said side walls adjacent said base portions of said fingers increases in the direction toward said surface at said free extremity of said fingers.

3. A finger bar according to claim 1 wherein said finger bar includes a leading edge for receiving and channeling pulp past a trailing edge and wherein said fingers have side walls extending generally lengthwise between said edges, said side walls of adjacent fingers being oriented in a divergent manner relative to each other from the finger bar's leading to trailing edges.

5. In a pulpstone grinder for producing pulp from a supply of material comprising:

a pulpstone mounted for rotational movement, said pulpstone having a peripheral grinding surface;

at least one pocket adjacent to the pulpstone periphery for receiving a supply of material to be processed and directing same against said pulpstone; the improvement comprising:

a first finger bar position transversely of and in close proximity to the pulpstone periphery and adjacent a trailing side of said pocket to modify the flow of materials processed .by said pulpstone and carried from said pocket, said first finger bar having a plurality of laterally spaced, angularly oriented fingers angled transversely relative to the rotational axis of said pulpstone;

said first finger bar, including fi ngers each of which includes a generally planar surface at the free extremity thereof, said first finger bar further including a base portion between opposed side walls of adjacent fingers and defining therewith a spacing between said opposed side walls, said opposed side walls of adjacent fingers being inclined relative to each other such that said spacing between said side walls adjacent said base portions of said fingers increases in the direction toward said surface at said free extremity of said fingers;

said first finger bar including a leading edge for receiving and channeling pulp past a trailing edge and wherein said fingers side walls extend generally lengthwise between said edges, said side walls of adjacent fingers being oriented in a divergent manner relative to each other from the finger bars leading to trailing edges; and

a second finger bar position transversely of and in close proximity to said pulpstone periphery and located at a leading pocket side to impede sliver movement and thereby subsequently reduce the slivers to pulp, said second finger bar having a plurality of laterally spaced, straight fingers oriented in line with the radii of said pulpstone, said first and second finger bars defining said pocket.

5. A grinder accordirigTo cTaihTz wherein said improvement further comprises a plurality of pockets radially spaced about the circumference of said pulpstone, each pocket cooperating with a magazine radially spaced adjacent to said pocket for supplying material to be processed therein.

6. A finger bar adapted for use in a pulpstone grinder with a rotatably mounted pulpstone, said bar comprising:

a top wall,

a rear wall extending perpendicularly to said top wall,

a bottom wall extending perpendicularly to said rear wall and parallel to said top wall, said bottom wall being smaller than said top wall,

a front wall extending perpendicularly to said bottom wall and parallel to said rear wall, said front wall being smaller than said rear wall,

7. A finger bar as defined in claim 6 wherein said fingers are divided directionally into two sets at the center of said bar, one set of fingers extending laterally outwardly toward one axial end of said bar pulpstone, and the other set extending laterally outwardly toward the opposite axial ends of said bar and pulpstone. 

1. A finger bar adapted for use in a pulpstone grinder with a rotatably mounted pulpstone, said bar comprising: a plurality of laterally spaced fingers positioned transversely relative to the longitudinal axis of said finger bar, said fingers being oriented relative to each other such that the spacing between the side walls of adjacent fingers increases in the direction of pulpstone rotation whereby pulp jamming and material buildup between adjacent fingers is reduced.
 2. A finger bar according to claim 12 wherein each of said fingers includes a generally planar surface at the free extremity thereof, said bar further including a base portion between opposed side walls of adjacent fingers and defining therewith the spacing between the opposed side walls, said opposed side walls of adjacent fingers being inclined relative to each other such that the spacing between said side walls adjacent said base portions of said fingers increases in the direction toward said surface at said free extremity of said fingers.
 3. A finger bar according to claim 12 wherein said finger bar includes a leading edge for receiving and channeling pulp past a trailing edge and wherein said fingers have side walls extending generally lengthwise between said edges, said side walls of adjacent fingers being oriented in a divergent manner relative to each other from the finger bar''s leading to trailing edges.
 4. In a pulpstone grinder for producing pulp from a supply of material comprising: a pulpstone mounted for rotational movement, said pulpstone having a peripheral grinding surface; at least one pocket adjacent to the pulpstone periphery for receiving a supply of material to be processed and directing same against said pulpstone; the improvement comprising: a first finger bar position transversely of and in close proximity to the pulpstone periphery and adjacent a trailing side of said pocket to modify the flow of materials processed by said pulpstone and carried from said pocket, said first finger bar having a plurality of laterally spaced, angularly oriented fingers angled transversely relative to the rotational axis of said pulpstone; said first finger bar, including fingers, each of which includes a generally planar surface at the free extremity thereof, said first finger bar further including a base portion between opposed side walls of adjacent fingers and defining therewith a spacing between said opposed side walls, said opposed side walls of adjacent fingers being inclined relative to each other such that said spacing between said side walls adjacent said base portions of said fingers increases in the direction toward said surface at said free extremity of said fingers; said first finger bar including a leading edge for receiving and channeling pulp past a trailing edge and wherein said fingers'' side walls extend generally lengthwise between said edges, said side walls of adjacent fingers being oriented in a divergent manner relative to each other from the finger bars leading to trailing edges; and a second finger bar position transversely of and in close proximity to said pulpstone periphery and located at a leading pocket side to impede sliver movement and thereby subsequently reduce the slivers to pulp, said second finger bar having a plurality of laterally spaced, straight fingers oriented in line with the radii of said pulpstone, said first and second finger bars defining said pocket.
 5. A grinder according to claim 15 wherein said improvement further comprises a plurality of pockets radially spaced about the circumference of said pulpstone, each pocket cooperating with a magazine radially spaced adjacent to said pocket for supplying material to be processed therein.
 6. A finger bar adapted for use in a pulpstone grinder with a rotatably mounted pulpstone, said bar comprising: a top wall, a rear wall extending perpendicularly to said top wall, a bottom wall extending perpendicularly to said rear wall and parallel to said top wall, said bottom wall being smaller than said top wall, a front wall extending perpendicularly to said bottom wall and parallel to said rear wall, said front wall being smaller than said rear wall, a projecting face extending between said front wall and said bottom wall at an angle inclined to a vertical plane passing through the front wall, said face having a plurality of vertically inclined, angularly oriented slots defined therein, said slots being laterally spaced from one another by angularly oriented fingers, said fingers and said slots being arranged to direct pulp toward the axial ends of the pulpstone.
 7. A finger bar as defined in claim 6 wherein said fingers are divided directionally into two sets at the center of said bar, one set of fingers extending laterally outwardly toward one axial end of said bar pulpstone, and the other set extending laterally outwardly toward the opposite axial ends of said bar and pulpstone. 